The present invention relates generally to bleed valves used in systems comprising a pressurized fluid. More specifically, the present invention relates to methods and apparatus for automatically venting a portion of a fluid from at least a portion of a pressurized system.
Pressurized systems typically comprise a pressurized fluid, such as a liquid or gas, which is contained within the system at a pressure that is different from the pressure of the environment surrounding the system. A pressurized system may also comprise a valve for venting a portion of the pressurized fluid to change the pressure of the fluid or to equalize the pressure of the fluid of the system with the pressure of the surrounding environment. Such a valve for venting a portion of the pressurized fluid may be referred to herein as a “vent,” “bleed valve,” “venting valve,” or “release valve.”
FIG. 1 illustrates an example of a pressurized system 38 comprising a first pressurized device 40 connected to a second pressurized device 42 through a pressurized passage 48. The pressurized passage 48 may be connected to the first pressurized device 40 through a first releasable interface 44 and to the second pressurized device 42 through a second releasable interface 46. The first releasable interface 44 and the second releasable interface 46 may each be configured to prevent the passage of -a fluid (not shown) when closed and to allow the passage of the fluid when opened. When the first releasable interface 44 and second releasable interface 46 are both open, a pressurized fluid may flow between the first pressurized device 40 and the second pressurized device 42 through the pressurized passage 48. For example, if the first pressurized device 40 is at a higher pressure than the second pressurized device 42 when the first releasable interface 44 and second releasable interface 46 are opened, the pressurized fluid will flow from the first pressurized device 40 to the second pressurized device 42 until the relative pressures of the first pressurized device 40 and the second pressurized device 42 are equalized or one of the pressurized interfaces 44, 46 are closed.
By way of example, the pressurized system 38 may be used to fill scuba tanks or other pressurized devices with a compressible fluid. Thus, for example, the first pressurized device 40 may comprise a pressurized air source used to fill or pressurize the second pressurized device 42 which in turn may comprise, for example, a scuba tank. As another example, the first pressurized device 40 may comprise a large scuba tank used to fill a smaller scuba tank (i.e., the second pressurized device 42) with compressed air.
An artisan will recognize that the pressurized system 38 can be adapted to accommodate a wide range of fluid pressures. For example, scuba tanks are typically rated to withstand air pressures ranging from approximately 1800 PSI (i.e., approximately 124 bar) to approximately 3000 PSI (i.e., approximately 206 bar) or higher in the United States. In other countries, scuba tanks are rated to withstand air pressures ranging from approximately 3000 PSI (i.e., approximately 206 bar) to approximately 4500 PSI (i.e., approximately 310 bar).
The pressurized system 38 may also comprise a vent 50 coupled to the pressurized passage 48. The vent 50 may also be coupled to a vent controller 52 configured to manually open and close the vent 50 to alter the pressure of the fluid in at least a portion of the pressurized system 38. For example, if the first releasable interface 44 is closed and the second releasable interface 46 is open, opening the vent 50 with the vent controller 52 will alter the pressure in the passage 48 and the second pressurized device 42. Similarly, if both releasable interfaces 44, 46 are closed, opening the vent 50 will only alter the pressure of the fluid in the passage 48.
FIG. 2 illustrates an adapter 54, such as the model 910C refill adapter available from Submersible Systems, Inc. of Huntington Beach Calif. The adapter 54 comprises a screw 56 and a yoke 58 configured to attach the adapter 54 to a first pressurized device (not shown), such as a scuba tank or other pressurized container. The adapter further comprises a fitting 60 configured to provide a fluid passage from the first pressurized device to a second pressurized device (not shown). The fitting 60 includes a vent hole 62 and a bleed screw 64 configured to open and close the vent hole 62. The bleed screw 64 comprises a threaded stem 67 and a sealing device 68, such as an o-ring or soft seat.
Charging adapters or refill adapters, such as the adapter 54 shown in FIG. 2, typically need a vent or release valve incorporated into their design to relieve the pressure on the fittings. For example, as shown in FIG. 3, the adapter 54 may be threaded onto a regulator 66, such as the “Spare Air” regulator available from Submersible Systems, Inc., located in Huntington Beach, Calif. Typically, when filling a pressurized container (not shown) configured to attach to the regulator 66, the adapter 54 is threaded onto the regulator 66 by the action of fingertips or special tools (not shown). For example, a user can grip the fitting 60 by hand and screw it onto the regulator 66.
When the fitting 60 is not under pressure, screwing it onto the regulator 66 requires overcoming only a small resistance, such as that required to compress an o-ring (not shown). However, to unscrew and remove the adapter 54 from the regulator 66 requires that the fluid pressure be discharged from the fitting 60. Typically, removing the adapter 54 from the regulator 66 involves first turning the bleed screw 64 by hand to release the pressure on the threads of the fitting 60 and then turning the fitting 60 by hand to unscrew it from the regulator 66.
FIG. 4 illustrates instructions for filling a pressurized tank, referred to as “SPARE AIR,” from a scuba tank using a refill adapter, such as the adapter 54 shown in FIG. 2. As the instructions indicate, the operation of filling the pressurized tank is complicated by the need to turn two different valves in a particular sequence. In fact, if the instructions are not followed, the act of refilling will not even occur. For example, in normal operations, an operator must first screw the adapter to the corresponding threaded part. This is typically a one-way check valve on the device to be filled. Then, before opening the valve that would allow the gas or fluid to travel from the storage device or fill station, the operator must first be sure to close the vent valve of the adapter to prevent the contents from leaking out the fittings instead of refilling the device. The same problem arises after the device to be recharged is full. After shutting off the main flow control valve from the storage tank or refill station, the operator must now open the vent valve by turning it in the opposite rotation used to close it.
Typically, even experienced operators may make a mistake and not remember to close the vent before starting to fill, or attempt to unscrew it without first relieving the pressure. This would make it very difficult or impossible to unscrew due to the increased pressure load on the threads. This sometimes leads to the operator employing a hammer or large wrench in order to break free what are thought to be slightly stuck threads. In some cases this forcing action can shorten the life-span of the parts or even result in a sudden failure of the parts involved. This can also produce a small explosion of compressed gas that can cause the adapter or pieces thereof to fly through the air, possibly resulting in injury.
Further, the construction of some existing types of vent valves has been prone to easily, yet accidentally, unscrewing the vent valve so much that it is completely removed from the vent hole and lost. Additionally, some existing devices are prone to wear over time and have a tendency to either develop leaks or, even worse, completely fail under pressure, which could lead to serious injury.
Thus, it would be advantageous to develop a technique and device for automatically venting a fluid from a pressurized system to allow an element or component of the system to be safely removed from the system.